1. Field of the Invention
The invention relates to a preparation method for a boron fertilizer, and more particularly to a preparation method for a weak acidic boron fertilizer comprising high content of pure boron.
2. Description of the Related Art
The content of pure boron in conventional boron fertilizers is normally lower than 20%. Such a boron fertilizer is known as a low-content boron fertilizer and generally used as a base fertilization, i.e. root fertilization. The boron fertilizer with pure boron content higher than 20% is known as a high-content boron fertilizer and generally used as foliar fertilization. At present, all high-content boron fertilizers at home and abroad are obtained by dehydrating borax decahydrate under a temperature of 350-450° C. The pure boron content in such high-content boron fertilizers is 21.48% in theory while in fact it is 20-21%, and with the following disadvantages:                1. production costs are high due to complicated production process and large energy consumption;        2. since the obtained boron fertilizer is alkaline, it is slow in dissolution rate and poor in compounding performance; and        3. pure boron content cannot be further increased.        